A Heterogeneous Network (abbreviated to HetNet and also called “Heterogeneous Hybrid Network”) is proposed as one of countermeasures against an increase of traffic in a network formed by a macrocell. The heterogeneous network is a network including a macrocell and one or a plurality of small cells disposed within the macrocell. With the small cells being disposed within the macrocell, it is feasible to increase a receivable user count and/or a network frequency band. The small cell includes a microcell, a picocell and a femtocell.
For further information, refer to Japanese Patent Laid-Open Publication No. 2003-037555, Japanese Patent Laid-Open Publication No. 2010-212998, International Publication WO2010/110187, Japanese Patent Laid-Open Publication No. H10-336727, Japanese Patent Laid-Open Publication No. 2002-111912, Japanese Patent Laid-Open Publication No. H07-123153 and Examine Patent Publication No. S62-059940.
The HetNet has a problem of causing a rise of total power consumption of small cell base stations with an increase of the number of small cells disposed within the macrocell. ON/OFF operations of each small cell are conducted manually in status quo. The operation of setting OFF an unnecessary small cell for reducing the power consumption entailed the operator's monitoring a state of using each small cell and setting OFF the small cell deemed unnecessary, and was therefore highly complicated.
It is assumed that a terminal in communication exists when the small cell deemed unnecessary is set OFF. The terminal attempts handing over to a base station forming the macrocell. The handover may be rejected depending on a traffic state of the macrocell at that time. As a result, the terminal is disabled from detecting the handover target cell, resulting in an interruption of the communication.